Yes, TICKER is a Scrabble word!

Letter values in Scrabble US: T 1, I 1, C 3, K 5, E 1, R 1.

Is it a valid word?

TICKER is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the hollow muscular organ located behind the sternum and between the lungs; its rhythmic contractions move the blood through the body
a small portable timepiece
a character printer that automatically prints stock quotations on ticker tape

Also: stock ticker.